Consolidation Loan

Can someone please explain to me how does consolidation works? If you take another loan from an existing loan and the Loan is approved then there is a potion taken to pay the existing loan and the remainder of the new loan is given to you. I did not get the amount paid to the existing loan but when I settle my balance that amount is still charged so I end up paying the existing loan with a new loan but I did not get that money. It supposedly paid the existing loan so I pay twice the bank. Where I could have just had two separate loans at different branches this is *******